1. Technical Field
The present disclosure relates to a communication technology, and more specifically, to methods of flow control for dual connectivity in a mobile communication network.
2. Related Art
Recently, uses of a variety of mobile devices (e.g., smart phone, tablet personal computer (PC), etc.) are increasing. Accordingly, the amount of traffics is rapidly increasing. It has a limitation to process the traffic caused by the increasing mobile devices by using the conventional networks. In order to overcome the above problem, a small cell technology can be introduced.
A small cell may have a coverage with a radius smaller than 200 meters. On the contrary, a macro cell may have a coverage with a radius of 20 kilometers. A base station supporting the small cell may have a smaller size in comparison with a base station supporting the macro cell. Therefore, it takes smaller costs to install the base station supporting the small cell in comparison with the base station supporting the macro cell. For example, the base stations supporting the small cells can be installed in coverage holes of the macro cells (e.g., edge regions of macro cells) thereby improving network performance. Also, the small cell may offload the traffic of the macro cell thereby improving network performance.
Meanwhile, a terminal (user equipment; UE) supporting dual connectivity may be connected simultaneously with a base station supporting a macro cell (hereinafter, referred to as a ‘master eNB (MeNB)’) and a base station supporting a small cell (hereinafter, referred to as a ‘secondary eNB (SeNB)’), and transmit/receive data packets. In the above dual connectivity environment, the MeNB may be connected to the SeNB via a non-ideal backhaul. In this case, errors may occur in data packets transmitted from the MeNB to the SeNB.
Also, the SeNB may transmit the data packets received from the MeNB to the UE. Due to a communication failure between the SeNB and the UE, a situation that the UE does not receive the data packets transmitted by the SeNB may occur. In this situation, the SeNB may receive new data packets from the MeNB even when data packets to be transmitted to the UE are still stored in a buffer. Therefore, load in the SeNB may increase if a proper flow control operation is not performed between the base stations.